SparkFun Electronics Commentsurn:uuid:214d0e4e-f1b1-d287-ce26-ac5b4c9f82492015-03-31T14:48:39-06:00SparkFun Electronicsmisk84 on WIG-09840 - Button Pad Controller SPImisk84urn:uuid:37b9a13d-9986-55d0-a367-3cf8c1e5e7612012-02-13T10:09:49-07:00<p>Thanks, Sparkfun!
<a href="http://vimeo.com/35886494" rel="nofollow" >Our Extended TicTacToe Game</a></p>pmscientist on WIG-09840 - Button Pad Controller SPIpmscientisturn:uuid:985c5d2f-94c2-6c79-fb29-e98d4581bdfd2012-02-06T19:09:34-07:00<p>You might take a look at the LoL shield. It does the same thing. Essentially when both sourcing and sinking current via the ICs used, 74LS595 and ULN2803 respectively, there is enough current limiting in the system that current limiting resistors aren&rsquo;t necessary in this case.</p>Remnant on WIG-09840 - Button Pad Controller SPIRemnanturn:uuid:139f7bd3-d4d4-e8e8-0491-07bec464d65d2012-02-06T15:18:22-07:00<p>I&rsquo;m curious how this (and the other button controller) gets away with running the LEDs directly from the shift register with no current limiting resistors? Is the output impedance of the shift reg high enough to limit the LED current itself, and if so does this put undue stress on the shift register?</p>